1. Field of the Invention
The present invention relates to an apparatus and a method for manufacturing a semiconductor device.
2. Description of the Related Art
Conventionally, a technique for packaging a semiconductor chip on a die pad of a lead frame by resin molding so as to expose the chip to an outside is developed. For example, U.S. Pat. No. 5,622,873 (corresponding to JP Patent No. 3,630,447) discloses a process for manufacturing a solid type image pick-up device. In the process, an image pick-up chip (a semiconductor chip), which is wire-bonded to leads of the lead frame, is packaged by resin molding by using an upper mold having a stepped projection of a size corresponding to a light-receiving region. Thus, a resin mold has a cavity through which the light-receiving part of the image pick-up chip is exposed to the outside.
The above-described manufacturing process can improve productivity compared with a manufacturing process, in which the image pick-up chip is attached to a cavity in a chip-receiving vessel formed by sintering, before the image pick-up chip is wire-bonded to a chip pad. In addition, U.S. Pat. No. 5,622,873 discloses that when the upper mold has a groove at a bottom of the stepped projection, the stepped projection is separated from the light-receiving region of the image pick-up chip. Therefore, the light-receiving region of the image pick-up chip can be prevented from contamination during a process of the resin molding.
However, in a typical image pick-up device, a distance between the light-receiving region and an adjacent pad for wire bonding is set to be about 0.1 to 1 mm. Therefore, at the bottom of the stepped projection, it is difficult to form the groove at a portion corresponding to the light-receiving region by using a mold with a normal accuracy required for a typical resin molding, while arranging a concave part surrounding the groove (i.e., the most projected portion of the stepped projection 20a which is located at both sides of the groove 20′a in FIG. 7 in U.S. Pat. No. 5,622,873) within an area separated from the pad for wire bonding, i.e., within the above-described distance.
Thus, in the manufacturing process disclosed in U.S. Pat. No. 5,622,873, the upper mold having the stepped projection is required to be formed with a high accuracy. However, a cost of the upper mold is generally increased with accuracy, and a production cost of the image pick-up device is increased with an equipment cost. Further, a life of a microfabricated mold tends to be short compared with a mold for the typical resin molding. As a result, an equipment cost and a production cost may increase.
Additionally, in order to position the most projected portion of the stepped projection 20a within the area smaller than 1 mm, the stepped projection is required to be positioned within an accuracy of 10 μm with respect to the image pick-up chip bonded to the lead frame. Thus, the lead frame is required to be positioned with a high accuracy in a horizontal direction, and a carrying system of the lead frame is required to be changed to meet the high accuracy. Therefore, the equipment cost and the production cost may further increase.
As described above, in the manufacturing process disclosed in U.S. Pat. No. 5,622,873, various problems are caused by increasing the accuracy of the mold. It is difficult to prevent the light-receiving region from contamination, i.e., to improve a reliability of the image pick-up device, without increasing the accuracies of the mold and the carrying system. Thus, a yield rate and a mass productivity may be reduced.